1.0 Field of the Invention
This invention relates to databases; and in particular, this invention relates to a non-disruptive backup copy in a database online reorganization environment.
2.0 Description of the Related Art
Databases allow a user to conveniently store and access data. Various databases store data in datasets. To allow data in a database to be recovered in the event of a failure, a database administrator periodically makes a backup copy of the dataset. The backup copy may also be referred to as an image copy. The backup copy may be a full image copy of the entire dataset, or an incremental image copy which comprises the differences in the dataset with respect to a previous backup copy. The previous backup copy may be a full image copy or another incremental image copy.
A dataset typically changes over time as data is added to, deleted from or updated in the dataset. Therefore, over time unused empty space forms among the data in the dataset because of the changes, and the dataset is referred to as being fragmented. Fragmentation typically degrades the performance of the database. For example, the amount of time to search for data in the dataset may increase. The database administrator typically uses a process referred to as reorganization to remove the empty space from the dataset. Reorganization may be performed while the dataset is online, that is, while users can access and change the dataset.
One database management system does not allow image copies to be created for datasets undergoing Online Reorganization (OLR) until OLR is complete. Therefore, there is a need for a technique which allows a backup copy of a dataset to be created while that dataset is undergoing online reorganization.